Research On Fractional Order Control Strategy Of Photoelectric Stabilized Aiming Platform

The photoelectric stabilized aiming platform mainly constitutes a servo control loop through the feedback of the gyroscope to isolate the motion interference of the carrier,so as to maintain the stability of the platform body and the loaded optical load,so as to achieve accurate aiming and tracking of the target.It is mostly used in military combat with aircraft,ships,combat vehicles and other carriers.However,due to the complex and changeable working environment,it is always affected by various torque interference,high-frequency measurement noise and other factors,which leads to the decrease of the visual axis stability accuracy of the loaded optical load,and finally deviates or loses the target information.Therefore,this paper takes the photoelectric stabilized aiming platform in the form of two-axis and two-frame structure as the research object,and aims to improve the control performance and control accuracy of the servo system.The main work of the article is as follows:1)The composition and structure of the photoelectric stabilized aiming platform system are analyzed,and the factors affecting the visual axis stability accuracy of the photoelectric stabilized aiming platform are studied.Secondly,the mechanism modeling of each component of the speed loop stability loop of the photoelectric stabilized aiming platform is carried out.The integer order mathematical model is established by using the frequency domain identification method,and the fractional-order mathematical model is obtained by using a variable order algorithm.2)Based on the fractional-order model of the speed loop stabilization loop of the photoelectric stabilized aiming platform,a fractional-order PID controller is designed.The approximation effect of the standard and improved Oustaloup discretization algorithms on the fractional calculus operator is analyzed.The fractional-order model and controller are numerically realized.Aiming at the problem that the traditional parameter tuning method of fractional-order PID controller is complex and difficult to program,the linear decreasing weight particle swarm optimization(LDWPSO)algorithm and the optimal index rule are combined to optimize the parameters of fractional-order PID controller.Finally,the stability of the designed fractional-order PID control system is analyzed,and the numerical simulation comparison is carried out.The results show that the fractional-order PID controller has natural advantages over the fractional-order model,and has better response speed and dynamic response characteristics.3)In order to further improve the disturbance suppression ability of the system,a fractional-order control strategy based on improved disturbance observer is proposed.Based on the structure of fractional-order PID control system,an improved disturbance observer is introduced to improve the problem that the classical disturbance observer enlarges the sensor measurement noise.The robust stability of the system is analyzed when the cont rolled object undergoes model perturbation.The design method of the low-pass filter in the improved disturbance observer is given.Finally,the numerical simulation comparison verifies that the proposed control strategy has better dynamic response,anti-interference ability and robustness.4)In order to verify the practical application effect of the proposed control strategy,the software design of servo system based on DSP is carried out,and the corresponding test is carried out in the photoelectric stabilized aiming experimental platform.The dynamic performance experiment and stability accuracy experiment of the photoelectric stabilized aiming platform under PID control,fractional-order PID control and fractional-order control strategy based on improved disturbance observer are carried out.It is verified that the fractional order control strategy based on improved d isturbance observer has certain advantages in dynamic response and disturbance suppression ability.